1. Field
The present disclosure generally relates to devices and methods related to copper interconnects for compound semiconductors.
2. Description of the Related Art
Compound semiconductor devices use metals such as gold to form interconnecting lines such as bus lines. These interconnects are commonly referred to as Metal 1, Metal 2 and Metal 3. Metal 1 or M1 typically refers to a first layer of metal interconnects that contacts, for example, ohmic metals and other active and/or passive components (e.g., resistors, capacitors and inductors) associated with integrated circuits. Metal 2 or M2 typically refers to a layer that connects to the M1. Metal 3 or M3 typically refers to, for example, a heat spreader in devices such as power amplifiers.
Gold is selected for some or all of the foregoing applications due to its properties such as low electrical resistivity, chemical inertness and desirable wire bonding properties. However, the price of gold is relatively high, thereby increasing costs associated with fabrication of compound semiconductor devices.